The motor grader may be the most elegant of all the titans on a job site. This long-necked creature is the sculptor of the crew, who makes the earth in the form of exact grades and slopes. However, it is not a problem-free machine, like any other complicated machine. Be it a brand new model or a reliable used motor grader, knowing the common problems is essential in reducing downtime and ensuring your projects are not delayed.
So, what are some of the most common headaches that operators and fleet managers have, and more importantly, how can you solve them?
1. The Engine Won’t Start or Is Hard to Start
There is nothing as irritating as inserting the key and hearing… nothing. Or even that dreadful, slow crank.
- Dead or Weak Battery: This is the most likely culprit. Graders possess huge diesel engines that are power-hungry to turn over. Inspect battery terminals, check for corrosion, and tighten. Check the voltage with a multimeter; a voltage of less than 12.6V means a weak or discharged battery.
- Bad Starter Motor: You may hear a positive click but no cranking. The starter solenoid or motor itself may be going bad. Listen to any abnormal grinding sounds, which may indicate that the starter gear is worn.
- Fuel System Problems: The fuel lines may have air in them, the fuel filter may be clogged, or the lift pump may be failing, which will not allow the fuel to reach the engine. Follow the manufacturer’s manual on bleeding the fuel system and replace filters on a rigid schedule.
2. Excessive Hydraulic Oil Temperature
The hydraulics of your used motor grader are its blood, and when that oil gets too hot, efficiency drops to zero, and parts will soon be damaged.
- Blocked Oil Cooler: The hydraulic oil cooler is a radiator; it requires airflow. The fins may become insulated by dirt, debris, and chaff that accumulates on them and blocks heat exchange. Cleaning the cooler should be included in your regular maintenance.
- Wrong Hydraulic Oil: It is possible to use the oil of wrong oil viscosity, which may break down under pressure and heat up quickly. Make sure you always use the grade of oil indicated in your machine manual.
- Internal Leaks or Relief Valve Problems: A continuously bypassing relief valve or internal leaks in pumps or cylinders cause the oil to have to work harder and produce unnecessary heat. This usually necessitates a pressure test and expert diagnosis.
3. The Blade Drifts or Won’t Hold Grade
This is the cardinal sin of a grader-the inability to keep a fixed cross-slope or grade. This compromises the whole essence of the machine.
- Worn Lift Cylinder Piston Seals: This is the most common reason for blade drift. Hydraulic fluid is leaking inside the lift cylinders past the seals, and gravity is slowly drawing the blade down. The fix is to repack the cylinders with new seals.
- Damaged Control Valves: The electronic or manual valves that regulate hydraulic flow to the cylinders may wear out or become contaminated, rendering them unable to hold pressure. A technician normally requires a diagnostic.
4. Unusual Noises from the Articulation Joint
That clunking or grinding sound when you turn isn’t just annoying. It’s a cry for help from a critical component.
- Worn Articulation Bearings: The massive bearings that allow the grader to articulate front and rear frames undergo tremendous stress. Lack of lubrication is their biggest enemy. Regularly grease them according to the service intervals. Once worn, they need to be replaced, which is a significant job.
- Loose King Pins or Bolts: Check for any visible play and ensure all pivot point bolts are torqued to the specified torque. A quick visual and physical check can often spot this simple fix.
5. Electrical Gremlins
From flickering lights to complete system failures, electrical problems can be the most perplexing.
- Corroded Connections and Grounds: Vibration and exposure to the elements cause wiring connections to loosen and corrode. A huge percentage of electrical faults are traced back to a poor ground connection. Clean battery terminals, chassis grounds, and sensor connectors regularly.
- Chafed Wiring: Engine vibration can cause wiring harnesses to rub against the frame or other components, eventually wearing through the insulation and causing a short circuit. Secure loose harnesses with zip ties away from sharp edges.
6. Steering Problems: Hard or Erratic
Fine grading work requires smooth, accurate steering.
- Checking Low Hydraulic Fluid: First, check the hydraulic reservoir. It is easy but quite frequently forgotten.
- Air in the System: When the steering feels spongy or the steering wheel is too hard to turn, it is possible that there is air in the hydraulic steering system. This will need bleeding the system, which is described in the service manual.
- Worn Steering Components: Steering components such as mechanical linkages, drag links, and tie-rod ends may wear out and cause slop in the steering system. The problem will be identified by a physical check of loose parts.
7. Poor Braking Performance
A 20-ton machine must stop dependably, each and every time.
- Contaminated Brake Linings: When your brakes are chattering or grabbing, oil or grease may have contaminated the brakes. This requires replacing the linings and, more importantly, locating and repairing the cause of the contamination (e.g., a leaking axle seal).
- Brake Lines (Air Brakes): Air in the lines of a grader with air-over-hydraulic brakes will result in a soft brake pedal. The system should be bled.
A used motor grader in good condition is an excellent asset. By taking note of these typical problems and mitigating them before they occur, you can make sure that your machine will continue to be a useful and accurate tool at your job site well into the future. Grease is cheap, repairs are not.
FAQs
Q1: What is the service interval of my used motor grader?
A: You should always use the recommended service intervals as shown in your operator manual. But when contractors acquire a used motor grader of unknown history, they should prudently perform a complete service (engine oil, all filters, hydraulic oil, and greasing) immediately. Under extreme operating conditions (extreme dust, mud, cold), it may be necessary to reduce the air and hydraulic filter change intervals.
Q2: What is the one maintenance item that is most critical to a motor grader?
A: Everything is important, but probably the most effective is diligent and proper greasing. It directly eliminates wear on costly parts such as articulation joints, blade circle, and cylinder pins. One greasing omission can severely increase wear.
Q3: Would a used motor grader be worth purchasing with these possible problems?
A: Absolutely. A used motor grader may be an immense value. The trick is due diligence: find a thorough service history, have a mechanic you trust inspect it pre-purchase with an eye toward the engine, hydraulics, and frame, and be willing to pay to have the most important wear items reconditioned immediately.
Q4: The controls of my grader are sluggish. What is it?
A: Slow controls are normally indicative of a hydraulic problem. Begin with the hydraulic fluid level and state. Then check the hydraulic filter. Assuming they are good, a worn-out hydraulic pump may fail to produce sufficient pressure or flow, and professionals need to test it.
